The November 2012 ballot in Arkansas will list only one candidate on the ballot for State Representative, district 54. He is Fred Smith, the Green Party nominee. His only ballot-listed opponent, incumbent Democrat Hudson Hallum, has resigned from the race and from the legislature. See this story. Arkansas permits write-in votes in the general election, so it is not a certainty that Smith will win.
Assuming Smith does win, this will be the second time the Green Party has elected a state legislator in Arkansas by virtue of being in a race in which no other party had a nominee on the general election ballot. The first time was in 2008, when Richard Carroll was elected. He remained in the Green Party for a year, and got a bill through the legislature expanding the petitioning period for newly-qualifying parties from two months to three months. But then he switched to the Democratic Party, and he lost the Democratic primary in 2010.